<?php
/**
 * CodeIgniter
 *
 * An open source application development framework for PHP
 *
 * This content is released under the MIT License (MIT)
 *
 * Copyright (c) 2014 - 2016, British Columbia Institute of Technology
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 * THE SOFTWARE.
 *
 * @package    CodeIgniter
 * @author    EllisLab Dev Team
 * @copyright    Copyright (c) 2008 - 2014, EllisLab, Inc. (https://ellislab.com/)
 * @copyright    Copyright (c) 2014 - 2016, British Columbia Institute of Technology (http://bcit.ca/)
 * @license    http://opensource.org/licenses/MIT	MIT License
 * @link    https://codeigniter.com
 * @since    Version 3.0.0
 * @filesource
 */
defined('BASEPATH') OR exit('No direct script access allowed');

/**
 * PDO ODBC Database Adapter Class
 *
 * Note: _DB is an extender class that the app controller
 * creates dynamically based on whether the query builder
 * class is being used or not.
 *
 * @package        CodeIgniter
 * @subpackage    Drivers
 * @category    Database
 * @author        EllisLab Dev Team
 * @link        https://codeigniter.com/user_guide/database/
 */
class CI_DB_pdo_odbc_driver extends CI_DB_pdo_driver
{

    /**
     * Sub-driver
     *
     * @var    string
     */
    public $subdriver = 'odbc';

    /**
     * Database schema
     *
     * @var    string
     */
    public $schema = 'public';

    // --------------------------------------------------------------------

    /**
     * Identifier escape character
     *
     * Must be empty for ODBC.
     *
     * @var    string
     */
    protected $_escape_char = '';

    /**
     * ESCAPE statement string
     *
     * @var    string
     */
    protected $_like_escape_str = " {escape '%s'} ";

    /**
     * ORDER BY random keyword
     *
     * @var    array
     */
    protected $_random_keyword = array('RND()', 'RND(%d)');

    // --------------------------------------------------------------------

    /**
     * Class constructor
     *
     * Builds the DSN if not already set.
     *
     * @param    array $params
     * @return    void
     */
    public function __construct($params)
    {
        parent::__construct($params);

        if (empty($this->dsn)) {
            $this->dsn = 'odbc:';

            // Pre-defined DSN
            if (empty($this->hostname) && empty($this->HOSTNAME) && empty($this->port) && empty($this->PORT)) {
                if (isset($this->DSN)) {
                    $this->dsn .= 'DSN=' . $this->DSN;
                } elseif (!empty($this->database)) {
                    $this->dsn .= 'DSN=' . $this->database;
                }

                return;
            }

            // If the DSN is not pre-configured - try to build an IBM DB2 connection string
            $this->dsn .= 'DRIVER=' . (isset($this->DRIVER) ? '{' . $this->DRIVER . '}' : '{IBM DB2 ODBC DRIVER}') . ';';

            if (isset($this->DATABASE)) {
                $this->dsn .= 'DATABASE=' . $this->DATABASE . ';';
            } elseif (!empty($this->database)) {
                $this->dsn .= 'DATABASE=' . $this->database . ';';
            }

            if (isset($this->HOSTNAME)) {
                $this->dsn .= 'HOSTNAME=' . $this->HOSTNAME . ';';
            } else {
                $this->dsn .= 'HOSTNAME=' . (empty($this->hostname) ? '127.0.0.1;' : $this->hostname . ';');
            }

            if (isset($this->PORT)) {
                $this->dsn .= 'PORT=' . $this->port . ';';
            } elseif (!empty($this->port)) {
                $this->dsn .= ';PORT=' . $this->port . ';';
            }

            $this->dsn .= 'PROTOCOL=' . (isset($this->PROTOCOL) ? $this->PROTOCOL . ';' : 'TCPIP;');
        }
    }

    // --------------------------------------------------------------------

    /**
     * Platform-dependant string escape
     *
     * @param    string
     * @return    string
     */
    protected function _escape_str($str)
    {
        $this->db->display_error('db_unsupported_feature');
    }

    // --------------------------------------------------------------------

    /**
     * Determines if a query is a "write" type.
     *
     * @param    string    An SQL query string
     * @return    bool
     */
    public function is_write_type($sql)
    {
        if (preg_match('#^(INSERT|UPDATE).*RETURNING\s.+(\,\s?.+)*$#is', $sql)) {
            return FALSE;
        }

        return parent::is_write_type($sql);
    }

    // --------------------------------------------------------------------

    /**
     * Show table query
     *
     * Generates a platform-specific query string so that the table names can be fetched
     *
     * @param    bool $prefix_limit
     * @return    string
     */
    protected function _list_tables($prefix_limit = FALSE)
    {
        $sql = "SELECT table_name FROM information_schema.tables WHERE table_schema = '" . $this->schema . "'";

        if ($prefix_limit !== FALSE && $this->dbprefix !== '') {
            return $sql . " AND table_name LIKE '" . $this->escape_like_str($this->dbprefix) . "%' "
            . sprintf($this->_like_escape_str, $this->_like_escape_chr);
        }

        return $sql;
    }

    // --------------------------------------------------------------------

    /**
     * Show column query
     *
     * Generates a platform-specific query string so that the column names can be fetched
     *
     * @param    string $table
     * @return    string
     */
    protected function _list_columns($table = '')
    {
        return 'SELECT column_name FROM information_schema.columns WHERE table_name = ' . $this->escape($table);
    }
}
